Monica: It takes time to start over. It's best you never had children with your ex and take it slow with the new person. Don't let your ex hold the key to your happiness/sense of self worth.
It's good you have accepted his betrayal. You will be able to forgive him eventually which will help you close this chapter. Please realize that if you were to reunite, the trust would have weakened and you would have been walking on eggshells and not thriving in a healthy relationship.
You're on the right path seeking encouragement from your support network and accepting your new path.
I do understand how you feel also. My husband left me for another woman after 29 years. We would have been married for 30 years this month. We never had any children and I have no family. I have a great support network of friends that I am thankful for. I also have a strong faith.I keep busy and have a lot of interests and a career. I have been attending counseling also. It just is not enough though. I feel that there is a large part of my life missing that can not be filled. I just keep thinking of all the years I wasted with him.
Pray and ask God to help you. We don't now how,when, what or where. Perhaps this guy came for a reason. If you are not ready i'm not suggesting you date him, but you may want to kee him as a friend or an ally. Like me I know you are probably not thinking about dating.